there is a very simple entity bean generator for mysql

[johnhollon]

package com.jdi.dbport.utils;
import java.sql.*;
import java.io.*;

/**
 * Create Entity Bean (byte code) from existing tables in database.
 * This generator can only generate basic code for programming, so
 * you should optimize the generated code.
 * before you use this tool, be sure that there is a folder called
 * "001_JDI_Generate_EntityBean_TEMP" in the root of C hard driver.
 * @author CHR
 *
 */

public class GenerateEntityBeans {
 private static String packageName = "com.jdi.persistence";
 private static String directory = "C:\\001_JDI_Generate_EntityBean_TEMP\\";

 StringBuffer start = new StringBuffer()
 .append("/** Generated Entity Bean - YOU SHOULD OPTIMIZE IT - Copyright (C) ??? */\n");

 StringBuffer packagingAndImporting = new StringBuffer()
 .append("package " + packageName + ";" + "\n" +
 "import javax.persistence.*; \n" +
 "import java.util.*; \n" +
 "import java.sql.*; \n" +
 "import java.math.*;\n\n");

 private StringBuffer doGenerateClassName(String tablename,String classname){
 String classdeclaring =
 "@Entity \n " +
 "@Table(name=\"" + tablename + "\") \n " +
 "public class " + classname +"{\n";
 StringBuffer mainclasstext = new StringBuffer().append(start).append(packagingAndImporting);
 mainclasstext.append(classdeclaring);
 return mainclasstext;
 }

 private StringBuffer doGenerateProperties(String columnname, String datatype, String keytype,
String nullable, String defaultvalue){
 String useddatatype;
 String compareString = datatype.concat("111111111");
 //Integer,Int,Mediumint,tinyint,smallint as int
 if(compareString.substring(0,7).equalsIgnoreCase("Integer")||compareString.substring(0,3).equalsIgnoreCase("Int")||
 compareString.substring(0,9).equalsIgnoreCase("MEDIUMINT")||compareString.substring(0,8).equalsIgnoreCase("SMALLINT")||
 compareString.substring(0,7).equalsIgnoreCase("TINYINT"))
 useddatatype = "int";
 //bigint as long
 else if(compareString.substring(0,6).equalsIgnoreCase("BIGINT"))
 useddatatype = "long";
 //float,double,decimal,real,numeric as double
 else if(compareString.substring(0,5).equalsIgnoreCase("FLOAT")||compareString.substring(0,6).equalsIgnoreCase("DOUBLE")||
 compareString.substring(0,7).equalsIgnoreCase("DECIMAL")||compareString.substring(0,4).equalsIgnoreCase("REAL")||
 compareString.substring(0,7).equalsIgnoreCase("NUMERIC"))
 useddatatype = "double";
 //char, varchar, date, datetime, timestamp as String
 else if(compareString.substring(0,4).equalsIgnoreCase("CHAR")||compareString.substring(0,7).equalsIgnoreCase("VARCHAR")||
 compareString.substring(0,4).equalsIgnoreCase("DATE") ||compareString.substring(0,8).equalsIgnoreCase("DATETIME") ||
 compareString.substring(0,9).equalsIgnoreCase("TIMESTAMP"))
 useddatatype = "String";
 else useddatatype = "String";
 String propertiesclaring1 = "\tprivate " + useddatatype + " " + columnname + ";\n";
 String propertiesclaring2 = "\t@Column(name=\""+ columnname +"\")\n";
 String propertiesgetter = "\tpublic " + useddatatype + " get" + columnname + "(){\n\t\treturn " + columnname +";\n\t}\n";
 String propertiessetter = "\tpublic void " + "set" + columnname + "(" + useddatatype + " " + columnname + "){\n\t\tthis." + columnname + " = " + columnname + ";\n\t}\n\n";
 String propertiesID = "\t@Id\n\t@GeneratedValue\n";
 StringBuffer propertiesText = new StringBuffer().append(propertiesclaring1);
 if(keytype!=null && keytype.equalsIgnoreCase("PRI"))
 propertiesText.append(propertiesID);
 propertiesText.append(propertiesclaring2).append(propertiesgetter).append(propertiessetter);
 return propertiesText;
 }

 private StringBuffer doGenerateJavaCode(Connection conn, String tablename,String classname){
 StringBuffer javaCode = new StringBuffer();
 javaCode.append(doGenerateClassName(tablename,classname));
 String querycolumns = "show columns from " + tablename;
 try{
 Statement stmt = conn.createStatement();
 ResultSet rs = stmt.executeQuery(querycolumns);
 while(rs.next()){
 javaCode.append(doGenerateProperties(rs.getString("Field"),rs.getString("Type"),
 rs.getString("Key"),rs.getString("Null"),rs.getString("Default")));
 }
 rs.close();
 stmt.close();
 javaCode.append("\n}");

 }catch(Exception e){
 System.out.println(e.getMessage());
 }
 return javaCode;
 }

 private void writeToFile(StringBuffer sb, String filename){
 try{
 File out = new File(filename);
 FileWriter fw = new FileWriter(out);
 for (int i = 0; i < sb.length(); i++){
 char c = sb.charAt(i);
 fw.write(c);
 }
 fw.flush();
 fw.close();
 }catch(Exception e){
 System.out.println(e.getMessage());
 }
 }
 public GenerateEntityBeans (Connection conn, String tablename, String classname, String directory){
 writeToFile(doGenerateJavaCode(conn,tablename,classname),directory);
 }
 public static void main(String args[]){
 try{
 Class.forName("com.mysql.jdbc.Driver").newInstance();
 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/jdi","jdi","jdi");
 String query1 = "show tables";
 Statement stmt = conn.createStatement();
 ResultSet rs = stmt.executeQuery(query1);
 while(rs.next()){
 String tablename = rs.getString(1);
 String classname = tablename + "EntityBean";
 new GenerateEntityBeans(conn,tablename,classname,directory + classname + ".java");
 }
 stmt.close();
 rs.close();
 conn.close();
 }catch(Exception e){
 System.out.print(e.toString());
 }finally{
 ;
 }

 }
}